In reality, there are many many reasons why Indian parents (even mothers!) prefer to give birth to a son. Some of the reasons I have seen around me are -
1. More sons means more earners for the family (This is true for poorer income groups where the girls are either not sent to school at all or sent only to primary schools)
2. Sons will stay with the parents (Since in Indian culture, girls have to marry and stay with the husband's family as a custom here!)
3. With girls, dowry is seen as an additional expenditure. Similarly, when parents have son, they see son getting dowry home (Source of income!)
4. Notion of 'keeping the name alive' - Sons are meant to carry forward the family name (sirname) as daughters change their second name after that of their husband's.
5. Many women suffer in the hands of their mother-in-laws (Via domestic violence etc.). So, they don't want their daughters to suffer and hence, want to give birth only to sons!

Having said that, however, the situation seems to be changing now and people in general have started respecting women more. This is mainly because Indian women are doing well for themselves financially, becoming ambitious and having started living life on their own terms rather than on other's expectations.

For once Banyan, you've given us some good news. This is very very heartening. As a teacher once at a night-school, I can never get over the determination and grit shown by those little girls, who swept homes during the day and attended class at night. Their bright shiny eyes and tiny dreams of becoming a police inspector or a nurse told me decades ago that the future of this country (and indeed any) was in the empowerment, development and progress of its women. But there's lots to do yet, so much... so much.

I am certain of the points made by 'guest-wnasanm' also that education and equal opportunities are extremely crucial.

In most parts of India, I see girls in rural areas coming out of their former 'back of the house' enforced isolation, into schooling and with good school-leaving certificates, confidently seeking jobs - and getting them as fast as their male counter-parts.

Turning to history, I cannot locate a worse era for female infanticide, despite the preference for baby boys, than the 1980s and 1990s.

In Traditional India, 'garbha-sisu vadha' [foetus- baby killing] was considered one of the five major sins [Pancha Maha Pathakas], liable to taint a family for seven generations.

That fear melted away somehow in our times. Pity.

I hope, better sense prevails.

Except in some towns in Northern India, in most other parts of the country, I think 'sex selection' and 'termination' are socially disapproved of. If at all some crazies go for it, they would have to do it very secretively.

Very true, today even in rural areas parents are wanting to liberate themselves from the ills of dowry and are turning to educate their daughters as an escape from this curse. Yet the preference for male children persists even among the educated progressive South Indian communities. I clearly remember congratulating my cousin on the birth of his second daughter, to be told with a nod, that it was hardly an moment of pride. Subsequently he had a son. Today 25 years later both daughters are Post-graduates having done professional courses independent and doing very well in large financial institutions. The son dropped out from college. This may not be case everywhere. Call it my bias, but I firmly believe that given the same opportunities women do better. They also manage homes and work and in any field can outdo their masculine counterparts.

Although the correlation of income may help to demonstrate (in this article) in which way this practice swings, but I strongly feel that its incorrect. What I personally think makes a huge difference is how the society perceives women. Equal opportunities for women in all walks of life can influence the notion among those who believe (or are made to believe due to societal pressure e.g. dowry)that girls are liabilities. Therefore education and I repeat equal opportunity can make a difference. The example of South Korea's GDP per person of $12000 is just a figure and conclusions based on that shouldn't be drawn.

India? The problem was never worst in India. This is an East Asian problem, pure and simple. East Asia is fundamentally different from India, and until there are signs of hope from East Asia, the problem cannot really be said to be turning a corner in any way.

In countries where selective abortion has made girls significantly scarcer than boys, why doesn't this automatically cause girls to be perceived as more valuable? (e.g. reversing the direction of dowry so it becomes "bride price").

The where is your house, where is your car problem...
Currently there is over-supply of girls in Urban China and over supply of boys in Rural China for this reason. In the end, all this will leads is breakdown of marriage and family structure in China, with higher divorce rate and more people prefer not to be marriage. (All are already happening in China) Which would further suppress birth rate.

At the risk of appearing politically incorrect,India's population growth is unsustainable and will have to be brought in line with economic and environmental realities by some means. Education of women and giving them rights is by far the best and most moral way to achieve this. Government birth quotas are the most oppressive and demoralizing method. Unfortunately, China under Mao, the ultimate totalitarian, chose the worst possible population control method and got the worst possible long term results.

It is because women are not free to make these choices. When women are scarcer, the "price" is kept artificially low by (forced, unofficial) fraternal polyandry which is prevalent in Punjab and Rajasthan. Another new practice is to import brides from the southern state of Kerala, where the sex ratio is healthier.

One point that no one seems to mention is that the healthier sex ratio in some states is at least partly due to the IT and call center industry. These firms provide safe, well-paying jobs in big cities that is encouraging an entire generation of women to rely on career rather than marriage for their financial security.

I think that may have more to do with the services of sex selection and abortion. Relatively richer China have more of these services avaliable.
But according to the latest 2010 Chinese census, the boys to girls ratio has dropped 0.53 point from the 2005 census, a small improvement.